Method of treating tubular knitted fabrics



Aug, 9, 1955 F. R. REDMAN 2,714,756

METHOD OF TREATING TUBULAR KNITTED FABRICS Filed oct. 8, 1952 2 sheets-sheet 1 E E @i gg, Egg

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METHOD OF TREATING TUBULAR KNITTED FABRICS Filed OCT.. 8, 1952 2 Sheets-5h66?. 2

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/fca for United States Patent O METHOD OF TREATING TUBULAR KNITTED FABRICS Frank R. Redman, Yardley, Pa.

Application October 8, 1952, Serial No. 313,623

7 Claims. (Cl. 26e-18.5)

This invention relates to treatment of tubular knitted fabrics and, its principal object is to minimize shrinkage and to effect uniformity of residual shrinkage lengthwise and widthwise of the fabric.

It is now recognized in the art that shrinkage of gar ments made from tubular knitted fabrics is caused by an unnatural condition of the fabric at the time garments are made therefrom. To explain this, tubular knitted fabric is stretched lengthwise or elongated by the treatment to which it is subjected subsequent to knitting of the fabric and prior to the cutting thereof in the subsequent manu facture of garments. ln its stretched or elongated condition, the fabric stitches are elongated lengthwise and narrowed widthwise, and they tend to acquire a distorted set Ordinary treatment of the fabric prior to the making of garments therefrom does not undo this distorted set, but the laundering of garments does so due to the agitation to which the fabric is subjected in laundering. The undoing of this distorted set relieves the stitches and permits them to return substantially to their normal condition, i. e. the normal shape and position that the stitches had immediately after knitting of the fabric and prior to rolling or other treatment thereof. Consequently, the laundering of the garments made from distorted fabric causes shrinkage of the garments, resulting in shortening and widening of the garments. It is now known that in order to minimize or substantially eliminate shrinkage of garments made from tubular knitted fabrics, it is necessary to restore the fabric substantially to its normal or natural condition prior to the making of garments therefrom.

In my prior Patent No. 2,597,530, issued May 20, 1952, there is disclosed and claimed a treatment process designated therein, and commercially known, as normalizing. The normalizing treatment comprises internally expanding the tubular knitted fabric widthwise, while it is free lengthwise, to effect shortening or condensing of the fabric, and permitting the fabric to relax. rl`he widthwise expansion of the fabric, while it isfree lengthwise, serves to relieve or undo the above-mentioned distorted set of the knitted stitches, and upon relaxing of the fabric the stitches are permitted to loosen and return generally to their normal shape and position, the object being to restore the fabric substantially to its natural or normal condition.

The method according to the present invention comprises expanding the fabric widthwise while it is sufficiently free lengthwise to relieve the distorted stitch loops, then permitting the fabric to relax in all directions so that it is completely relaxed both lengthwise and widthwise, and then applying steam tothe fabric while it is completely relaxed. The extent to which the fabric must be expanded and given lengthwise freedom to relieve the stitch loops depends upon the degree of distortion of the fabric. If the stitch loops ofthe fabric are not greatly distorted the widthwise expansion required to relieve the distorted stitch loops will be less than in the case of fabric in which the stitch loops are l j of the treatment.

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21,714,756 patented Aug. 9, 1955 greatly distorted and hence must be expanded widthwise to a substantial degree. Thus if the fabric, after knitting, has merely been rolled up, it will have been subjected only to theitension incident to rolling, and since it will not be greatly distorted, it will require only a slight degree of expansion. But if the fabric has been subjected to wet processing, i. e. bleaching and dyeing, it will have been subjected to relatively great tensions, and since it will be greatly distorted, it will require a substantial degree of expansion. If the fabric is dry at the time of treatment according to this invention, it` may be expanded and relaxed in its dry condition and then subjected to the application of steam while the fabric is completely relaxed. If the fabric is: wet or moist at the time of treatment according to this invention, it may be expanded and relaxed while in the wet or moist condition, then dried while completely relaxed, and then subjected to the application of steam while it is still completely relaxed.

I have found that the application of steam to the completely relaxed fabric, as an adjunct to the previous operation to relieve the stitch loops, effects consistent and uniform shrinkage reduction both lengthwise and widthwise of the fabric and thus serves to stabilize the fabric. While I have no desire to be bound by any particular theory, I believe that the effects of the steam application may be explained as follows.

One explanation of the effects of the application of steam to the completely relaxed fabric, as an adjunct to the previous normalizing treatment, has to do with the fibers which compose the yarns of which the fabric is knitted. Each yarn is composed of a multitude of small fibers, and there are multitudinous liber ends projecting from the yarn which `are scarcely visible to the naked eye. It is postulated that when. the fabric is expanded to relieve the stitch loops and then relaxed, the projecting fibers of the yarns resist the free sliding of the yarns over one another due to a tendency of the fibers to adhere or cling to one another especially where the yarns loop each other, and this tends to inhibit free return of the knitted stitches fully to their normal shape and position. It is further postulated that the heating and moistening effect of the steam on the fabric yarns serves to loosen the grip of the projecting fibers of the yarns on one another and thus permits free return of the stitches to their normal shape and position.

Another explanation of the effects of the application of steam to the completely relaxed fabric, as an adjunct to the previous expanding treatment, has to do with the stitches themselves. In this connection, it is postulated that the expanding of the fabric, while relieving the elongated distorted set of the stitches, does not cornpletely remove all of the kinks or bends in the stitch yarns where they loop each other, and the kinks or bends remain in some degree as a hangover from the stretched condition of the fabric. It is further postulated that the residual kinks or bends in the yarns tend to inhibit free return of the stitches to their normal shape and position, and that the heating and moistening effect of the applied steam softens the yarns and effectively removes the residual kinks or bends, thus permitting free return of the stitches to their normal shape and position.

Either or both of the above explanations may be valid, but whatever the true explanation, experimental use of this invention has proved the efficacy thereof.

The method of treating tubular knitted fabric according to this invention may be carried out in various apparatus arrangements. By way of example, certain arrangements are shown in the accompanying drawings for the treatment of fabric either when it .is dry at the time of the treatment or when it is wet or moist at the time In the` drawing,

Figs. 1 and 2 are illustrations of a section of tubular knitted fabric showing the fabric in its normal condition and in a greatly distorted condition;

Fig. 3 is a diagrammatic illustration of apparatus for treatment of dry fabrics;

Fig. 4 is a diagrammatic illustration of apparatus for treatment of Wet or moist fabrics; and

Fig. 5 is a diagrammatic illustration of apparatus which may be employed where it is desired to press the fabric to smooth it and finish it for width.

Referring rst to Figs. 1 and 2, Fig. 1 shows a section of tubular knitted fabric in the form in which it cornes from the knitting machine and prior to rolling or any other treatment. This is the normal or natural condition of the fabric in which the knitted stitches 11 have the shape illustrated and the fabric is completely free of tension or stretch in any direction. Accordingly, the fabric is entirely free of any distortion, either lengthwise or widthwise, and the stitches or loops are in a state of freedom. K

Fig. 2 shows how the fabric and the stitches thereof become distorted due to lengthwise tensions to which the fabric is subjected after knitting. As stated previously, the degree of distortion will depend upon the treatment to which the fabric has been subjected. Fig. 2 illustrates extreme distortion caused by great tensions to which the fabric is subjected in wet processing, i. e. dyeing and bleaching. It will be noted that in this condition the stitches 11 are elongated lengthwise of the fabric and are narrowed widthwise of the fabric, and the stitch yarns are taut. In this condition of the fabric, there is a definite distorted set of the stitches, the portions of the yarns which loop one another being sharply kinked or bent.

As previously described, the present invention effects restorationV of the stitches substantially to their normal shape and position, as shown in Fig. l, by subjecting the fabric to stitch relieving treatment by widthwise expansion of the fabric, while it is sufficiently free lengthwise, to relieve the distorted stitch loops, then permitting the fabric to relax in all directions so that it is completely relaxed both lengthwise and widthwise, and final-- ly applying steam to the fabric while it is completely relaxed and in a substantially dry condition. As previously indicated, the extent to which the fabric must be expanded and given lengthwise freedom to relieve the distorted stitch loops depends upon the degree of distortion of the widthwise to a substantial degree, while it is free lengthwise, in order to relieve the distorted stitch loops. After the distorted stitch loops have been relieved and the fab- Y v ric has been permitted to relax in all directions so that it is completely relaxed both lengthwise and widthwise, the application of steam to the fabric, while it is completely relaxed and in a substantially dry condition, causes the stitches to return to their normal condition as shown in Fig. 1. It should be noted that it is not necessary to apply the steam immediately after expanding and relaxing of the fabric. Steam may be applied at any time after expanding and relaxing the fabric provided that the fabric is maintained in a completely relaxed condition.

Figs. 3 to 5 are diagrammatic illustrations of apparatus arrangements which may be employed in the practice of this invention. Since all of the devices employed in these arrangements are known, the diagrammatic illustrations are suflicient for the purpose of this application.

Fig. 3 shows an arrangement which may be employed when the tubular knitted fabric is dry at the time it is to be treated according to this invention. In the arrangement shown, the dry fabric 10 is drawn from a basket or truck 12 over idler rolls 13 and 14 and over an expanding device 15 by power-driven rolls 16. Since the fabric is freely disposed in the basket or truck 12, it is free lengthwise and it may be expanded widthwise by the device 15 suiciently to relieve the distorted stitch loops of the fabric as previously described. The expanding device 15 may be of the character shown in my above-mentioned patent, or it may be of any other suitable form. The power-driven rolls 16 over-feed the fabric onto a powerdriven conveyor 17, so that the fabric is completely relaxed in all directions, and is completely relaxed both lengthwise and widthwise, as it is carried along by the conveyor 17. In this completely relaxed condition, the fabric has steam applied to one or both of its sides by any suitable steaming means. Preferably, steam is applied to both sides of the fabric by steam boxes 18 and 19 having outlet nozzles 20 and 21. The conveyor 17 deposits the fabric in a basket or truck 22.

Fig. 4 is a diagrammatic illustration of an apparatus arrangement for treatment of fabric which is in wet or moist condition. For example, such apparatus may be employed where the fabric to be treated has just come from wet processing and is in a wet condition. In the arrangement shown, the tubular knitted fabric 10 is drawn from a basket or truck 23 over idler rolls 24 and 25 and over an expanding device 26 by means of power-driven rolls 27, as in the arrangement of Fig. 3. Here again, the device 26 may be of the character shown and described in my above-mentioned patent or it may be of any other suitable form. The power-driven rolls 27 over-feed the fabric onto a power-driven inclined conveyor 28 so that the fabric is completely relaxed in all directions as it is carried along by the conveyor 28. The conveyor 28 feeds the fabric into a dryer 29 suitable for relaxed drying. Preferably the dryer is a basket dryer of the character disclosed and claimed in U. S. Patent No. 2,597,490, issued May 20, 1952 to A. O. Hurxthal. The basket conveyor 30 of the basket dryer comprises successive basket loops 31 which receive the fabric from the conveyor 28. The relative speeds of the conveyor 28 and the basket conveyor 29 are such that the fabric is loosely deposited in the basket loops 31, and, therefore, the fabric is completely relaxed as it is carried along by the basket conveyor. The dryer 29 further comprises means for subjecting the fabric to pressurized heated air to effect drying of the fabric as it is carried along by the basket conveyor. As illustrated, the pressurized air is applied to the fabric from ducts 32 and 33 having spaced outlet nozzles 34 and 35. The pressurized air enters the ducts through a common conduit 36 and an air heater 37. The basket conveyor 30 over-feeds the fabric onto a .powerdriven conveyor 38 so that the fabric is still completely relaxed as it is carried along by the latter conveyor. At this time, the fabric is in dry condition, and it is subjected to steam application by means of steam boxes 39 and 40 having outlet nozzles 41 and 42. The conveyor 38 deposits the fabric in a receiving basket or truck 43.

While the arrangements shown in Figs. 3 and 4 subject the fabric to the application of steam as the linal step in an uninterrupted treatment sequence, it is not necessary to apply steam to the fabric immediately after the spreading or expanding treatment as in Fig. 3, or immediately after the drying step as in Fig. 4. As long as the fabric is maintained in a completely relaxed condition, the steam treatment may be applied at any time after the previous treatment steps.

In the case of at least some tubular knitted fabrics,V it is necessary to flatten the fabric and press it to smooth it and to finish it for width. This not only improves the appearance of the fabric but it also better enables cutting thereof in the making of garments. If desired, this may be done prior to the application of steam to the fabric.

Fig. 5 shows an apparatus similar to that of Fig. 3 in which provision is made for attening and pressing the fabric as above mentioned. In the apparatus of Fig. 5, the fabric 10 is drawn from a basket or truck 44 over idler rollers 45 and 46 and over an expanded device 47 by power-driven rolls 48 which over-feed the fabric onto a power-driven conveyor 49. The conveyor 49 feeds the fabric to a flattening device 50 which may be in the form of an ordinary spreader adjusted merely to flatten the fabric and not subject it to any tension. The flattening device 50 extends into the nip of power-driven pressing rolls 51 which smooth the fabric and nish it for width. If necessary, the fabric may be moistened for pressing. The pressing rolls over-feed the fabric onto a powerdriven conveyor 52 so that the fabric is completely relaxed thereon. Steam is applied to the fabric by thc steam boxes 53 and 54. The conveyor 52 deposits the fabric into a basket or truck 55.

Similar provision for pressing the fabric can be made in the arrangement of Fig. 4, in which case the pressing may take place after the drying of the fabric.

From the foregoing description, it will be seen that the method according to this invention involves essentially expanding the tubular knitted fabric widthwise, while it is sufficiently free lengthwise, to relieve the distorted stitch loops, then permitting the fabric to relax in a directions so that it is completely relaxed both lengthwise and widthwise, and finally applying steam to the fabric while it is completely relaxed and in a substantially dry condition. The treatment thus involves relieving the distorted stitch loops, then permitting the fabric to rela" completely in all directions, and effecting free return or' the knitted stitches substantially to their normal shape and position by the application of steam while the fabric is completely relaxed and in a substantially dry condition.

It will be understood, of course, that the invention i". not limited to the specific disclosure hereof but contemplates such modifications or variations as may occur to those skilled in the art.

I claim:

1. A method of reducing shrinkage in tubular knitted fabric whereof the knitted stitch loops are distorted from their normal shape and position by treatment of the fabric subsequent to knitting thereof, which method comprises operating upon the fabric to relieve the distorted stitch loops, permitting the fabric to completely relax in all directions so that it is completely relaxed both lengthwise and widthwise, and applying steam to the fabric while it is completely relaxed.

2. A method of reducing shrinkage in tubular knitted fabric whereof the knitted stitch loops are distorted from their normal shape and position by treatment of the fabric subsequent to knitting thereof, which method comprises expanding the tubular fabric widthwise, while it is sufficiently free lengthwise, to relieve the distorted stitch loops, permitting the fabric to completely relax in all directions so that it is completely relaxed both lengthwise and widthwise, and applying steam to the fabric while it is completely relaxed and in a substantially dry condition.

3. A, method of reducing shrinkage in tubular knitted fabric whereof the knitted stitch loops are distorted from their normal shape and position by treatment of the fabric subsequent to knitting thereof, which method comprises expanding the tubular fabric widthwise, while it is sufficiently free lengthwise, to relieve the distorted stitch loops, permitting the fabric to completely relax in all directions so that it is completely relaxed both lengthwise and widthwise, flattening the fabric and pressing it to smooth it and to finish it for width, and applying steam to the fabric while it is completely relaxed and in a substantially dry condition.

4. A method of reducing shrinkage in tubular knitted fabric whereof the knitted stitch loops are distorted from their normal shape and position by treatment of the fabric subsequent to knitting thereof, which method cornprises expanding the tubular fabric widthwise and permitting lengthwise freedom thereof sufficiently to relieve the distorted stitch loops, permitting the fabric to completely relax in all directions so that it is completely relaxed both lengthwise and widthwise, and applying steam to the fabric while it is completely relaxed and in a substantially dry condition.

5. A method of reducing shrinkage in tubular knitted fabric whereof the knitted stitch loops are distorted from their normal shape and position by treatment of the fabric subsequent to knitting thereof, which method cornprises passing the fabric over an expanding device, while affording lengthwise freedom of the fabric, to relieve the distorted stitch loops, permitting the fabric to completely relax in all directions after it leaves said device so that it is completely relaxed both lengthwise and widthwise, and applying steam to the fabric while it is completely relaxed.

6. A method of reducing shrinkage in tubular knitted fabric whereof the knitted stitch loops are distorted from their normal shape and position by treatment of the fabric subsequent to knitting thereof, which method comprises expanding the tubular fabric in dry condition widthwise, while it is sufficiently free lengthwise, to relieve the distorted stitch loops, permitting the fabric to completely relax in all directions so that it is completely relaxed both lengthwise and widthwise, and applying steam to the fabric while it is completely relaxed and in a substantially dry condition.

7. A method of reducing shrinkage in tubular knitted fabric whereof the knitted stitch loops are distorted from their normal shape and position by treatment of the fabric subsequent to knitting thereof, which method comprises expanding the tubular fabric in wet or moist condition widthwise, while it is sufficiently free lengthwise, to relieve the distorted stitch loops, permitting the fabric to completely relax in all directions so that it is completely relaxed both lengthwise and widthwise, drying the fabric while maintaining it completely relaxed, and applying steam to the fabric while it is completely relaxed and in a substantially dry condition.

References Cited in the file of this patent UNITED STATES PATENTS 2,589,344 Cohn et al. Mar. 18, 1952 2,589,345 Cohn et al. Mar. 18, 1952 2,597,530 Redman May 20, 1952 

